Sep 12, 2026Procurement Guides
Stainless Steel Grades: Properties and Applications Compared
From 304 and 316 to duplex 2205 and 254 SMO, stainless steel grades differ in corrosion and heat performance. Compare the main grades here.
Quick answer: Stainless steel grades are grouped by microstructure - austenitic, ferritic, martensitic and duplex - and by what they resist. Type 304 and 316 cover most general and chloride service, stabilized grades 321 and 347 handle high temperature, and duplex 2205 and super-austenitic grades take on severe chloride and chemical duty.
Austenitic 304 and 316 Family
Type 304 and 304L are austenitic chrome-nickel stainless steels with general corrosion resistance, and they are non-magnetic except when cold worked. Type 304H carries higher carbon than type 304 for better high-temperature creep performance, with corrosion resistance the same as type 304, and it is intended for high temperatures above 1000 degrees Fahrenheit. Type 316 and 316L are also austenitic chrome-nickel steels, with improved corrosion and heat resistance and improved resistance to chlorides.
Grades for Higher Corrosion Resistance
Type 317L is an austenitic chromium-nickel-molybdenum stainless steel with improved resistance to chloride pitting compared with type 316, and it is used in the chemical, petroleum, pulp and paper industries. Type 904L is a low-carbon austenitic stainless steel with good resistance to pitting and crevice corrosion and resistance to reducing acids. Two further grades push chloride resistance further: 254 SMO is an austenitic stainless steel with high molybdenum content and high resistance to pitting, cracking and general corrosion, with very high resistance to chloride stress corrosion cracking; AL-6XN is also a high-molybdenum austenitic grade with excellent resistance to chloride corrosion and high resistance to salt water corrosion.
Heat-Resistant Grades
Type 309S is a high-quality heat-resistant austenitic stainless steel suitable for sustained exposure to 2000 degrees Fahrenheit, with slightly better corrosion resistance than type 304. Type 310S is a heat-resistant austenitic grade suitable for continuous exposure to 2100 degrees Fahrenheit, with general corrosion resistance better than type 304 and 309.
Stabilized Grades for High Temperature
Type 321 and 321H are austenitic stainless steels with titanium as a stabilizing element, giving improved intergranular corrosion resistance, and they suit high-temperature applications in the carbide precipitation range. Type 347 and 347H contain niobium as the stabilizing element, with the same benefit of improved intergranular corrosion resistance for high-temperature service in the carbide precipitation range.
Martensitic and Ferritic Grades
Type 410 is a martensitic stainless steel with high mechanical properties, more wear resistant than most 300 series stainless steels, and resistant to general corrosion and oxidation. Type 446 is a high-chromium ferritic stainless steel with excellent high-temperature oxidation and corrosion resistance, typically used for high-temperature applications.
Duplex Stainless Steel
Duplex 2205 is a duplex stainless steel made up of about 45 percent ferritic and 55 percent austenitic structure. It combines good strength, toughness and corrosion resistance and resists chloride stress corrosion cracking, which makes it a practical choice where both strength and chloride resistance are needed.
Grade selection is a balance: 304 and 316 cover most general and chloride duty, while stabilized, duplex and super-austenitic grades are reserved for high temperature or severe chloride and chemical service.
How SPAI STEEL Supplies Stainless Pipe
SPAI STEEL produces stainless and alloy steel pipe at its Longwan, Wenzhou base and supplies carbon steel from Jinghai, Tianjin. Founded in 1996 and part of the SP Group, the company exports to more than 100 countries and works to GB, API, ASTM, ASME/ANSI, BS, DIN, JIS and GOST standards. Third-party inspection by SGS, BV, TUV or TUBOSCOPE is available, along with cutting, slotting, coating, threading, grooving, custom fabrication, packing, marking and warehousing.
FAQ
What is the difference between 304 and 316 stainless steel?
Both are austenitic chrome-nickel grades, but 316 adds molybdenum for improved corrosion and heat resistance and better performance in chloride service.
Which stainless grade is best for high temperature?
Stabilized grades such as 321 and 347 are designed for high-temperature service, while 309S and 310S are heat-resistant grades for sustained high-temperature exposure.
When should duplex 2205 be used?
Duplex 2205 suits applications that need both higher strength and resistance to chloride stress corrosion cracking.
What makes 254 SMO different?
Its high molybdenum content gives very high resistance to chloride stress corrosion cracking, pitting and general corrosion.
Send SPAI STEEL the grade, size, standard and service conditions for your stainless pipe requirement. Our team will confirm a suitable material and arrange inspection, marking and delivery documentation.
